CIRCULATION

CIRCULATION

• THE CIRCULATORY SYSTEM ASSOCIATES INTIMATELY WITH ALL BODY TISSUES– CIRCULATORY SYSTEM• A SYSTEM OF INTERNAL TRANSPORT; TRANSPORTS

OXYGEN AND CARBON DIOXIDE, DISTRIBUTES NUTRIENTS TO BODY CELLS, AND CONVEYS THE WASTE PRODUCTS OF METABOLISM TO SPECIFIC SITES FOR DISPOSAL

CIRCULATION

• SEVERAL TYPES OF INTERNAL TRANSPORT HAVE EVOLVED IN ANIMALS– SIMPLE ANIMALS HAVE NO TRUE CIRCULATORY SYSTEM

(WHY DON’T THEY NEED ONE??)• EX. HYDRA

– BLOOD• SPECIALIZED CIRCULATORY FLUID FOUND IN MORE COMPLEX

ANIMALS– TWO BASIC TYPES OF SYSTEMS

• OPEN CIRCULATORY SYSTEM• CLOSED CIRCULATORY SYSTEM

CIRCULATION

• TWO BASIC TYPES OF SYSTEMS

CIRCULATION

• TWO BASIC TYPES OF SYSTEMS– OPEN CIRCULATORY SYSTEM• BLOOD LEAVES THE VESSELS AND BATH THE CELLS

DIRECTLY (EX. GRASSHOPPER)– CLOSED CIRCULATORY SYSTEM (A.K.A.

CARDIOVASCULAR SYSTEM)• CONSISTS OF A HEART AND TUBE-LIKE VESSELS; THE

BLOOD IS ALWAYS CONFINED TO THESE VESSELS (EX. FISH, HUMANS)

CIRCULATION

• CLOSED CIRCULATORY SYSTEM– THREE KINDS OF VESSELS

• ARTERIES– CARRY BLOOD AWAY FROM THE HEART– ARTERIOLES SMALL VESSELS, OFF ARTERIES, THAT GIVE RISE TO

CAPILLARIES• VEINS

– CARRY BLOOD TO THE HEART– VENULES RESULT OF CONVERGING CAPILLARIES THAT EVENTUALLY FORM

VEINS• CAPILLARIES

– CONVEY BLOOD BETWEEN ARTERIES AND VEINS WITHIN EACH ORGAN– CAPILLARY BEDS NETWORKS OF CAPILLARIES THAT INFILTRATE EVERY

ORGAN AND TISSUE IN THE BODY

CIRCULATION

• VERTEBRATE CARDIOVASCULAR SYSTEMS REFLECT EVOLUTION

CIRCULATION

• VERTEBRATE CARDIOVASCULAR SYSTEMS– PULMONARY CIRCUIT• CARRIES BLOOD BETWEEN THE HEART AND THE GAS

EXCHANGE TISSUES IN THE LUNGS– SYSTEMIC CIRCUIT• CARRIES BLOOD BETWEEN THE HEART AND THE REST

OF THE BODY

CIRCULATION

• HUMAN HEART AND CARDIOVASCULAR SYSTEM TYPIFY THOSE OF MAMMALS

CIRCULATION• FOLLOWING THE PATH OF BLOOD

– RIGHT VENTRICLE– *PULMONARY ARTERIES*– CAPILLARIES IN LUNGS– *PULMONARY VEIN*– LEFT ATRIUM– LEFT VENTRICLE– AORTA– ARTERIES BRANCH OFF AORTA– SUPERIOR VENA CAVA / INFERIOR VENA CAVA– RIGHT ATRIUM

– *VAVA L VAVA*

CIRCULATION

• THE STRUCTURE OF BLOOD VESSELS FITS THEIR FUNCTION– ARTERIES• THICKEST

– VEINS• VALVES

– CAPILLARIES• THINNEST

CIRCULATION• THE HEART CONTRACTS AND RELAXES RHYTHMICALLY

– CARDIAC CYCLE• A COMPLETE SEQUENCE OF

FILLING AND PUMPING OF THE HEART

• DIASTOLE– ENTIRE HEART IS RELAXED; BLOOD

FLOWS INTO ALL FOUR CHAMBERS» AV VALVES ARE OPEN,

ALLOWING BLOOD TO GOFROM ATRIUM TO VENTRICLES

• SYSTOLE– BRIEF CONTRACTION THAT FORCES

ALL BLOOD INTO VENTRICLES (0.1 SEC)– VENTRICLES CONTRACT FOR ABOUT

0.3 SEC, CLOSING AV VALVES AND OPENINGSEMI-LUNAR VALVES WHICH PUMPS BLOOD INTO ARTERIES

CIRCULATION• THE HEART CONTRACTS AND RELAXES RHYTHMICALLY

– CARDIAC OUTPUT• THE VOLUME OF BLOOD PER

MINUTE THAT THE LEFTVENTRICLE PUMPS INTO THESYSTEMIC CIRCUIT

– VALVES PREVENT BACKFLOWAND KEEP BLOOD FLOWINGIN RIGHT DIRECTION• RESPONSIBLE FOR “LUB-DUB”

SOUND HEART MAKES• WHEN DEFECTIVE, RESULTS IN

A MURMUR– EXTRA HEART SOUNDS

CIRCULATION

• THE PACEMAKER SETS THE TEMPO OF THE HEARTBEAT

CIRCULATION• THE PACEMAKER SETS THE TEMPO OF THE HEARTBEAT

– PACEMAKER A.K.A. SA (SINOATRIAL) NODE; SPECIALIZED REGION OF CARDIAC MUSCLE THAT MAINTAINS THE HEARTS PUMPING RHYTHYM BY SETTING THE RATE AT WHICH ALL THE MUSCLE CELLS OF THE HEART CONTRACT• PACEMAKER GENERATES ELECTRICAL SIGNALS• SIGNALS SPREAD THROUGHOUT ATRIA; 0.1 SEC TO REACH AV

(ATRIOVENTRICULAR) NODE• SPECIALIZED MUSCLE FIBERS RELAY SIGNALS AND CAUSE VENTRICLE

CONTRACTION THAT PUMPS BLOOD– ARTIFICIAL PACEMAKER

• A TINY ELECTRONIC DEVICE SURGICALLY IMPLANTED NEAR THE AV NODE; EMIT ELECTRICAL SIGNALS THAT TRIGGER NORMAL HEARTBEATS

CIRCULATION• WHAT IS A HEART ATTACK?

– HEART ATTACK• FAILURE OF THE HEART TO FUNCTION PROPERLY; DUE TO LACK OF

OXYGEN BEING DELIVERED TO CARDIAC CELLS– CARDIOVASCULAR DISEASE

• DISEASES OF HEART AND BLOOD VESSELS; ACCOUNTS FOR 40% OF ALL DEATHS IN U.S.

– ATHERIOSCLEROSIS• GROWTH OF PLAQUE

DEVELOPS ON THE INNER WALLS OF THE ARTERIES, NARROWING THE PASSAGES THROUGH WHICH BLOOD CAN FLOW

CIRCULATION

• BLOOD EXERTS PRESSURE ON VESSEL WALLS– BLOOD PRESSURE• THE FORCE THAT BLOOD EXERTS AGAINST THE WALLS

OF OUR BLOOD VESSELS– PULSE• THE RHYTHMIC STRETCHING OF

THE ARTERIES

CIRCULATION

• MEASURING BLOOD PRESSURE CAN REVEAL CARDIOVASCULAR PROBLEMS– HYPERTENSION• HIGH BLOOD

PRESSURE; MAY INDICATE A SEVERE CARDIOVASCULAR DISEASE

CIRCULATION

• SMOOTH MUSCLE CONTROLS THE DISTRIBUTION OF BLOOD– SPHINCTERS EXIST THAT LIMIT

BLOOD FLOW THROUGH CAPILLARY BEDS IF BLOOD IS NOT NEEDED IN THOSE AREAS (EX. DIGESTIVE TRACT DURING EXERCISE)

CIRCULATION

• CAPILLARIES ALLOW THE TRANSFER OF SUBSTANCES THROUGH THEIR WALLS– THE THIN WALLS MAKE THIS THE ONLY VESSEL

WHERE TRANSFER OF SUBSTANCES CAN TAKE PLACE

CIRCULATION

• BLOOD CONSISTS OF CELLS SUSPENDED IN PLASMA

CIRCULATION

• BLOOD CONSISTS OF CELLS SUSPENDED IN PLASMA– ADULT HUMAN ON AVERAGE HAS 4 – 6 LITERS OF

BLOOD– 4 PARTS TO BLOOD• PLASMA• RED BLOOD CELLS• WHITE BLOOD CELLS• PLATELETS

CIRCULATION

• PLASMA– LIQUID MADE UP OF 90% WATER, 10% INORGANIC

SALTS• 55% OF BLOOD IS PLASMA• WORKS TO MAINTAIN OSMOTIC BALANCE AND PH

CIRCULATION

• RED BLOOD CELLS– A.K.A. ERYTHROCYTES– MOST NUMEROUS BLOOD CELLS– LACK NUCLEI AND MITOCHONDRIA– FORMED IN BONE MARROW– CYCLE FOR 3-4 MONTHS BEFORE BROKEN DOWN AND

RECYCLED IN THE LIVER– *ANEMIA*

• AN ABNORMALLY LOW AMOUNT OF HEMOGLOBIN OR A LOW NUMBER OF RED BLOOD CELLS

CIRCULATION• WHITE BLOOD CELLS

– A.K.A. LEUKOCYTES– HELP DEFEND THE BODY– 5 TYPES

• BASOPHILS– RELEASE CHEMICALS TO FIGHT INFECTION

• NEUTROPHILS– PHAGOCYTES

• MONOCYTES– PHAGOCYTES

• EOSINOPHILS– KILL PARASITIC WORMS, HELP REDUCE ALLERGIES; NOT FULLY UNDERSTAND

• LYMPHOCYTES– KEY CELL IN IMMUNITY

– WILL DISCUSS IN MORE DETAIL DURING “IMMUNE SYSTEM”

CIRCULATION

• PLATELETS– BITS OF CYTOPLASM PINCHED OFF FROM LARGE

CELLS IN THE BONE MARROW– IMPORTANT IN BLOOD CLOTTING

CIRCULATION

• BLOOD CLOTTING– PLATELETS AND THE PLASMA PROTEIN FIBRINOGEN

ACT AS SEALANTS– PROTHROMBIN IS CONVERTED TO THROMBIN WHICH

CONVERTS FIBRINOGEN TO FIBRIN• FIBRIN

– THREAD-LIKE PROTEIN THAT TRAPS BLOOD CELLS; FORMING PATCH UNTIL CONNECTIVE TISSUE CAN HEAL

– CLOTTING MECHANISM DEFECTS CAN BE SERIOUS• HEMOPHILIA• THROMBOSIS CLOTS WHEN THERE IS NO INJURY

CIRCULATION

• STEM CELLS OFFER A POTENTIAL CURE FOR LEUKEMIA AND OTHER BLOOD CELL DISEASES– STEM CELLS• UNSPECIALIZED CELLS

– LEUKEMIA• CANCER OF THE WHITE BLOOD CELLS (LEUKOCYTES)

CIRCULATION

• SPEAKING OF DISEASES…HOW DOES THE HUMAN BODY PROTECT ITSELF??

• THE IMMUNE SYSTEM IS NEXT!!!